1. Field of Invention
This invention pertains to belt drive systems and, more specifically, to a belt tensioning mechanism used on a two belt drive system for a riding lawn mower.
2. Description of the Related Art
It is known in the art of lawn mowers to use a two belt drive system. Typically, a first belt provides power from a PTO (power take-off) pulley to a first pulley on a double stacked pulley. As is commonly known in the art, the PTO pulley is driven by the engine of the riding lawn mower. A second belt is used for providing power from the second pulley of the double stacked pulley to the spindle pulleys of the mower deck. The spindle pulleys are used to rotate cutting blades as is commonly known in the art.
Often when a two belt drive system is used the engine is positioned toward the front of the mower, the mower deck is positioned toward the middle of the mower and, the double stacked pulley is positioned toward the back of the mower. This is done so that as the double stacked pulley is moved in one direction, the two belts are simultaneously tensioned. Similarly, movement of the double stacked pulley in the opposite direction simultaneously de-tensions the two belts. De-tensioning of the belts places the belt system into an inoperative condition which is required when, for example, it is necessary to remover one of the belts and/or install a new one.
It is many times desirable however, to position the mower deck toward the front of the lawn mower and position the engine toward the rear of the mower. This necessitates positioning the double stacked pulley between the mower deck and the engine of the mower. This creates difficulties with the two belt drive system because as the double stacked pulley is moved one belt tends to be tightened while the other is simultaneously loosened. Therefore, it is difficult to place the belt system into an in operative condition.
What is needed for such a two belt drive system, is a mechanism and method for tensioning the first and second belts from an operative condition to a inoperative condition using a single tension arm.
Another problem known in the art of riding lawn mowers is related to the fact that typically as the mower deck is adjusted for height (thereby adjusting the distance between the cutting blades and the lawn being cut) the mower deck is also moved along the length of the mower frame. Such a mower deck height adjustment tends to negatively affect the belts of a two belt drive system.
In U.S. Pat. No. 5,361,566, Hohnl attempts to minimize the misalignment of the belts that typically occurs when the mower deck is height adjusted. What is still needed, however, is a mechanism and a method for balancing the tension on the two belts of a two belt system as the mower deck is height adjusted.
The present invention provides methods and apparatuses for balancing the belt tensions of a two belt drive system as the mower deck is height adjusted. The present invention also provides methods and apparatuses for simultaneously tensioning the first and second belts from an inoperative condition to an operative condition. The difficulties inherit in the art, are therefore overcome in a way which is simple and efficient, while providing better and more advantageous results.